I can envision a scenario where the native is donked but proton filled the gap for the non-native game, certainly has happened to me more than once.

At first that feels completely backwards, but I've had those kinds of experiences with other parts of Linux before, so I wouldn't be surprised.

Believe it or not I've experienced this with Uplink. There was a compiled linux native which refused to start, but the windows exe+proton ran ok. My rule of thumb is small indie developers tend to compile good linux runtimes, but large devs are a coin toss.

Yeah, that tracks.